Another layer of lightmap in top of the one that i already created it will only make a darker terrain ..

A secondary light map will help only in certans conditions:

1. if i make a special layer of hightmap (on top ) in which i generate a some detail with some fractal (Small Alien Hills for example) or drawn by brush , and keep this layer of detail ON only until the secondary lightmap is generated . After the secondary light map is generated disable the hightmap layer so that i will have detail only in the lightmap texture and not in the hightmap (because the detail from the hightmap can bring spikes to the terrain ..so we trying to avoid that).
2. the secondary lightmap must be without much contrast in order to bring detail only from far distance .

But again Grome is very flexible so you can create your one pipeline of work ..so feel free to post here any images created with Grome and explain your pipeline .

P.S
The island created for the tutorial is 8Km x 8 Km and the tile (distance between 2 vertices ) is 5 m ..so close to the resolution of a FPS . The time to make it (at the screens stage ) was 2 hours ...of course there are a lot of detail that need to be put in order to be a level..but my purpose so far is to create a tutorial for water and vegetation